ABSTRACT 



In 1976 and 1977, seabird and wading bird nesting colonies were inven- 

 toried along the northeast U.S. coast from Cape Elizabeth, ^!aine to the 

 Virginia-North Carolina border as part of a study conducted by the Massa- 

 chusetts Cooperative Wildlife Research Unit. A parallel study was conducted 

 for the rocky, island bound coastal region of Maine north of Cape Elizabeth 

 (Korschgen 1979). Colonies were surveyed and censused from Narch to July by 

 teams of highly-qualified field biologists using aerial and ground-based 

 methods. 



A total of about 240,982 pairs of waterbirds (28 species) nested at 512 

 colonies in 1977. The most abundant species, in order, were herring gulls, 

 laughing gulls, common terns, great black-backed gulls, snowy egrets, and 

 black-crowned night herons. Virginia and New Jersey harbored the largest 

 populations of waterbirds and also had the greatest area of coastal wetland 

 habitat. Wading birds usually arrive on the breeding ground and begin nesting 

 as early as late February and March, much earlier than most seabirds which 

 usually arrive in April (gulls) or May (terns). Substantial colony and yearly 

 variation exists in nesting chronology, but usually most waterbird young have 

 fledged by August. 



Evaluation of census techniques suggested that helicopters were the most 

 useful way to inventory colonies over this large region but were costly on a 

 per-hour basis. When aerial methods are employed, nest counts are required in 

 a number of "sample" colonies to establish an adult-to-nest ratio. This ratio 

 can then be applied to "correct" aerial estimates of adult numbers at other 

 colonies. For some conspicuous species such as double-crested cormorants, 

 great blue herons, great egrets, royal terns, and black skimmers, aerial 

 photography can be effectively used to count nesting adults. 



Historical nesting information indicated that most waterbi rd populations 

 had recovered from near extirpation caused by hunting in the ISOC's. While 

 populations of cormorants, herring and great black-backed gulls, cattle and 

 snowy egrets and glossy ibises are increasing, marked declines of Arctic, 

 roseate, and common terns have been documented in New England and New York. 

 Habitat alteration by oceanfront development, pollution, and competition with 

 more aggressive gull species for suitable colony sites are probably causally 

 related to this reduction. 



Because many colonies are located on land which is vulnerable to recrea- 

 tion and development pressures, careful monitoring and protection of nesting 

 waterbirds should be implemented. 



In addition to this report, an atlas has been prepared to include loca- 

 tion and nesting data for all waterbird colonies inventoried in 1977 from the 

 Maine-Canada border to Virginia (Erwin and Korschgen 1979). The atlas is 

 comprised of a series of maps showing individual colony sites and each map is 

 accompanied by a set of Tables with details of the nesting species and charac- 

 teristics of the colony sites. 



XV 



